[r9etb]

Only cancer is more destructive than a government assuming powers not specifically deligated by those who created it.

The Constitution specifically delegates to the Federal Government the power to deal with insurrection. Article VI makes it quite plain that secession is an act of insurrection.

[SevenDaysInMay]

No. If secession from the Union were to have been included as a form of insurrection against the Union, it would have been in writing within the Constitution. The several states would not have surrendered their independence to a federal government otherwise. This is a 'powers reserved to the people and the several states issue', established not by law of the land but through repeated invasions of sovereign states by the federal government.

Only elements of South Carolina fired on federal troops who had refused to leave. That was an error made in haste.

An insurrection would have been to overthrow the federal government, such as if D.C. had been invaded and Lincoln with other high officials arrested as a new extra-Constitutional regime was installed, not just leaving the Union behind.